Anemia

Causes of Anemia

Anemia occurs when you do not have enough red blood cells. Red blood cells are important because they carry hemoglobin, an iron-rich protein that attaches to oxygen and carries it to tissues throughout the body. Anemia can be due to problems making red blood cells, dysfunctional red blood cells, or red blood cells dying quickly. Anemia is diagnosed when a blood test shows a hemoglobin value of less than 13.5 g/dL for men or less than 12.0 g/dL for non-pregnant women. Normal values for children and pregnant women vary with age and trimester, respectively.

The Role of Red Blood Cells in Anemia

Symptoms of Anemia

When you have anemia, your body cannot bring oxygen to your tissues, other cells, and organs, so you may experience one or more of the following symptoms:

• Weakness
• Shortness of breath
• Dizziness
• Fast or irregular heartbeat
• Pounding or "whooshing" in your ears
• Headache
• Cold hands or feet
• Pale or yellow skin
• Chest pain

Am I at Risk for Anemia?

Many people are at risk for anemia because of poor diet, intestinal disorders, chronic diseases, infections, and other conditions. Women who are menstruating or pregnant and people with chronic medical conditions are most at risk for this disease. The risk of anemia increases as people grow older.

If you have any of the following chronic conditions, you might be at greater risk for developing anemia:

• Rheumatoid arthritis or other autoimmune disease
• Kidney disease
• Cancer
• Liver disease
• Thyroid disease
• Inflammatory bowel disease (Crohn disease or ulcerative colitis)

The signs and symptoms of anemia can easily be overlooked. In fact, many people do not even realize that they have anemia until it is identified in a blood test.

Sickle Cell Anemia

Sickle cell anemia is an inherited condition that causes malformed hemoglobin. This makes red blood cells sickle-shaped instead of round, rigid instead of flexible, and causes them to die faster than the body can replace them. This causes a chronic anemia. Additionally, rigid or sickled cells can clog blood vessels and cause pain, strokes, trouble breathing, and heart attacks, among other concerns.

Sickle cell anemia is a kind of sickle cell disease (SCD). Learn more about SCD here. 

Vitamin-Deficiency Anemia

Vitamin-deficiency anemia may result from low levels of vitamin B12, copper, zinc, or folate (folic acid). This can be due to not getting enough of these vitamins in one's diet, or due to the body not absorbing them properly. Patients with a history of alcohol use or bariatric surgery are at a higher risk of vitamin-deficiency anemia because their bodies have a harder time absorbing these nutrients. Pernicious anemia, a type of vitamin B12 deficiency, is an autoimmune condition that prevents vitamin B12 from being absorbed in the gastrointestinal tract. Pernicious anemia can be detected on routine blood tests and requires specialized treatment. Meanwhile, folate deficiency is less common due to more foods becoming fortified with folic acid, but certain patients are still at high risk.

Iron-Deficiency Anemia

Iron-deficiency anemia is the most common type of anemia. It happens when you do not have enough iron in your body. Iron is needed to make hemoglobin, the protein which carries oxygen throughout the body. Iron-deficiency anemia is usually due to blood loss (94% of cases) but may be due to poor dietary intake or the body not absorbing iron properly. Bleeding is the number one cause of iron-deficiency anemia. All men and non-menstruating women with iron-deficiency anemia should get an endoscopy and colonoscopy to rule out gastrointestinal cancers. Menstruating women with iron-deficiency anemia should talk to their healthcare providers about their periods and check for uterine abnormalities and bleeding disorders. Iron becomes even more important during pregnancy for both the mother and the baby, and pregnant patients can develop new-onset iron-deficiency anemia. People who have had gastric bypass surgery for weight loss or other reasons may also be iron deficient due to poor absorption.

Learn about Iron-Deficiency Anemia

Hemolytic Anemia

Hemolytic anemia occurs when red blood cells are broken up in the bloodstream or in the spleen. Hemolytic anemia may be due to mechanical causes (abnormal heart valves or aneurysms), infections, autoimmune disorders, bleeding disorders, or congenital abnormalities in the red blood cell. Patients with cirrhosis (liver dysfunction) can have destruction of red blood cells due to structural changes in their liver, spleen, and surrounding vessels. Hemolytic anemia can be inherited. Examples include some types of thalassemia and low levels of enzymes such as glucose-6 phosphate dehydrogenase. The treatment will depend on the cause.

Aplastic Anemia

Aplastic anemia is a rare disorder in which the bone marrow stops making enough red blood cells, white blood cells, and platelets. The disease can be inherited (e.g. Fanconi anemia, telomere disorders, Shwachman-Diamond syndrome, Diamond-Blackfan anemia, etc.) or acquired (caused by an autoimmune condition). In these cases, patients have lower numbers of red blood cell-forming stem cells in the bone marrow. With limited red blood cell precursors, lower levels of red blood cells can circulate in the bloodstream. Viral infections, ionizing radiation, and exposure to toxic chemicals or drugs can trigger acquired aplastic anemia. Treatment can include red blood cell transfusions, injections or pills to increase bone marrow red blood cell production, immunosuppression, or, in some cases, bone marrow transplant.

Anemia Caused by Other Diseases

Some diseases can affect the body's ability to make red blood cells. For example, some patients with kidney disease develop anemia because the kidneys are not making enough of the hormone erythropoietin to signal the bone marrow to make new or more red blood cells. Chemotherapy to treat various cancers often impairs the body's ability to make new red blood cells, and anemia often results from this treatment. Anemia can also occur temporarily if the bone marrow feels inflamed and “turns off.” This can occur from autoimmune disease, medications, or infections.